When putting together my tester board I only had immediate access to 150uF for C103 and C106, but since I used some of my KSA1220AY/KSC2690AY at a gain of about 250 for my pair it is like 37500uF is filtering the IPS supply.
So like OS says, the product of the transistor gain and the capacitance is the real important thing and there is no magic value for either, just make that product as big as possible.
So like OS says, the product of the transistor gain and the capacitance is the real important thing and there is no magic value for either, just make that product as big as possible.
Usually, I use power on delay and DC protection for speaker using relay. But in my experiment I do not use speaker protection. I connect the speaker to amplifier > 1 second after power on.
Yes. You must use speaker protection.
Now I have components to build speaker protection. But I do not make PCB layout, yet. Maybe I will use veroboard.
I guess since OS has shown so many different configurations that it would be next to impossible to include this speaker protection into the design and he has not shown a preferred power supply topology. I'll have to keep these facts in mind when I do a final implementation into a real product.
Thanks Still4given,
I'll look into that ebay board. My question is are we looking to detect a failure or something else with these protection circuits? With most circuits in consumer audio devices is this something that is commonly included or are we just being anal about protecting our speakers from a potential future electrical failure?
Hope you have fun with those boards from Jason, I'm still waiting to see mine come in the mail. I'm sure you will have yours done long before I will and at least you have a setup to test and measure them. I need to purchase a bunch of new(surplus) test equipment at the local electronics surplus store.
I'll look into that ebay board. My question is are we looking to detect a failure or something else with these protection circuits? With most circuits in consumer audio devices is this something that is commonly included or are we just being anal about protecting our speakers from a potential future electrical failure?
Hope you have fun with those boards from Jason, I'm still waiting to see mine come in the mail. I'm sure you will have yours done long before I will and at least you have a setup to test and measure them. I need to purchase a bunch of new(surplus) test equipment at the local electronics surplus store.
protection
Hi Steven, here.http://www.diyaudio.com/forums/solid-state/248105-slewmaster-cfa-vs-vfa-rumble-176.html
#post 1754 second photo .you can expand the photo ,i use a protection circuit from Elektor, crescendo millenium amplifier.(http://www.raylectronics.nl/pdfs/Crescendo_Millennium_en.pdf
Hi Steven, here.http://www.diyaudio.com/forums/solid-state/248105-slewmaster-cfa-vs-vfa-rumble-176.html
#post 1754 second photo .you can expand the photo ,i use a protection circuit from Elektor, crescendo millenium amplifier.(http://www.raylectronics.nl/pdfs/Crescendo_Millennium_en.pdf
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Maybe someone can recommend a stereo volume/tone control preamp to use with the power amps in this thread.
Been looking hard for a stereo preamp with volume and high/bass control, maybe but not essential mid control.
Anyone have some info for me, I prefer to etch my own board, as compared to buying pre-soldered module.
As shipping to my country and customs is a real pain.
Regards
Been looking hard for a stereo preamp with volume and high/bass control, maybe but not essential mid control.
Anyone have some info for me, I prefer to etch my own board, as compared to buying pre-soldered module.
As shipping to my country and customs is a real pain.
Regards
idea for you --- build an 10 octave band equalizer. As a more flexible tone control for your system.
Many circuit diagrams can be found via Google.
-RM
May I just... add my 2 cents
A bit surprised by the question, to be honest
In fact, every good commercial amplifier has got protection circuit.
In most cases, it is a combined circuit, providing 3 major functions:
1) Soft start;
2) Speaker protection;
3) Amplifier protection.
When you switch on the amp, soft-start sequence is initiated, allowing the PSU with large capacitors charging them without current overload, also allowing the amp start nicely.
Then protection circuit checks that key parameters are within the thresholds, for example:
- DC offset at the amp output;
- Quiescent current of OPS;
- Heatsink temperature.
If everything is fine, it connects the speakers.
If not - in many cases it will send the amp to standby and indicate the problem.
If one of the problems arise during the amp operation - protection will disconnect the speakers and then act according to pre-defined algorithm.
There is a wide range of soft-start/protection solutions, starting from rather simple ones with limited functionality, ending with comprehensive micro-controller based ones.
As an example, I use Arduino micro-controller to watch the sensors and control the relays...
In Audiolab 8000x7, one of the channel started giving about 2.5 volts DC offset at the output - protection fired immediately. 2.5 volts is not really dangerous for the speakers, but it could be more. The reason was the capacitor failure in one of the channels. After capacitor replacement protection allowed normal operation of the amp again.
vzaichenko,
Thanks for the simple explanation of your thinking. I know that Esperado, Christophe, had a thread going on a very nice protection scheme, but it was rather complex to implement. I'll look for a simple solution as that is about all I would be capable of.
Thanks for the simple explanation of your thinking. I know that Esperado, Christophe, had a thread going on a very nice protection scheme, but it was rather complex to implement. I'll look for a simple solution as that is about all I would be capable of.
Yes, I saw the one from Esperado - very well-engineered. MOSFET relays - good choice. Bonsai recently had trouble with high-speed high-current offset - mechanical relay did not release the speaker
Thinking about moving in that direction as well - found a place where to buy MOSFET relays...
Realize sch from post #1882 on VSSA PCB. Few cuts here and wires there and you'll make it.
It makes sense to test this front-end sch and compare to basic VSSA amp which you already have.
Yes, I saw the one from Esperado - very well-engineered. MOSFET relays - good choice. Bonsai recently had trouble with high-speed high-current offset - mechanical relay did not release the speaker
Thinking about moving in that direction as well - found a place where to buy MOSFET relays...
I advocate a power supply with all needed protection integrated, but nobody showed any interest to try that. JLH used stabilized power supply with electronic current fuse, loudspeaker protection against DC voltage, symmetrical switch off of both polarities in his 80 W moshet amp. I used his ideas in my power regulator with all that, but it's not stabilized, it acts as a kind capacitance multiplier. I don't like to have a relay contact or mosfet in series with the loudspeaker.